Area Forecast Discussion
Issued by NWS Sioux Falls, SD

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250
FXUS63 KFSD 231114
AFDFSD

AREA FORECAST DISCUSSION
National Weather Service Sioux Falls SD
614 AM CDT Tue Apr 23 2019

.SHORT TERM...(Today and Tonight)
Issued at 342 AM CDT Tue Apr 23 2019

Skinny surface high pressure will shift off to the east today
allowing return flow to expand from west to east.  Expect clear
skies across the area today, but there could be a few high clouds
filtering into central South Dakota late in the day.  Atmosphere is
very dry above 800 mb, but in general don`t expect mixing that high.
 Have lowered dew points slightly in central South Dakota where the
mixing will be slightly better, but left dew points alone east of
the James River.

With increasing southwesterly winds and increasing temperatures
aloft, could be a bit of non diurnal temperatures tonight,
especially in exposed areas (such as the Buffalo Ridge).

.LONG TERM...(Wednesday through Monday)
Issued at 342 AM CDT Tue Apr 23 2019

Another pleasant day expected on Wednesday, but could see a few more
high clouds in advance of a front moving through the region
Wednesday evening.  With 850 hpa temperatures increasing 3-5 C over
Tuesday, temperatures should warm well into the 70s with a few 80s
possible along and west of the James River Valley.

Front moves through the area Wednesday night.  Not much in the way
of low level moisture to work with, but could see a stray passing
shower or two.

Cooler day across the region on Thursday with gusty northwest winds
expected with mixing.

Most impactful weather will be on the bookends of the weekend as a
series of troughs move through the region.  Leeward cyclogenesis is
expected Friday night across the western high plains.  Models have
come into better agreement on the placement with this system,
tracking the  surface low across Nebraska.  Elevated warm front
looks to try to lift north towards the southern CWA Friday evening
as a very strong low level jet feeds into the boundary. Precipitable
water values approach the 90 percent moving average for this time of
year around an inch.  Moist adiabatic lapse rates don`t lend to a
lot of instability, but with strong convergence across the area
expected showers throughout the overnight.  Have raised pops through
the overnight hours.

Showers will gradually work out of the area on Saturday as the low
lifts towards the Great Lakes region.

A second low is expected to develop on Sunday moving across the
plains Sunday night into Monday.  The track of this system is
uncertain at this time, with the GFS favoring a northerly track, and
the ECMWF, GEM and German Models all tracking the wave across the
Central Plains.  This could result in another chance for
precipitation,  with cooler temperatures expected to begin next
week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 614 AM CDT Tue Apr 23 2019

Satellite picking up on some shallow fog through the mid portions
of the Big Sioux valley around Brookings, and to a lesser extent
for isolated locations immediately along the James River. These
spots should not impact TAF sites, which will remain VFR through
12z Wed.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

$$

SHORT TERM...BT
LONG TERM...BT
AVIATION...Chapman



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